Etching composition for an under-bump metallurgy layer and method of forming a bump structure using the same

ABSTRACT

In an etching composition for an under-bump metallurgy (UBM) layer and a method of forming a bump structure, the etching composition includes about 40% by weight to about 90% by weight of hydrogen peroxide (H 2 O 2 ), about 1% by weight to about 20% by weight of an aqueous basic solution including ammonium hydroxide (NH 4 OH) or tetraalkylammonium hydroxide, about 0.01% by weight to about 10% by weight of an alcohol compound, and about 2% by weight to 30% by weight of an ethylenediamine-based chelating agent. The etching composition may effectively etch the UBM layer including titanium or titanium tungsten and remove impurities. A method of forming a bump structure may employ such an etching composition.

BACKGROUND

1. Technical Field

Exemplary embodiments relate to an etching composition for an under-bumpmetallurgy (UBM) layer, and a method of forming a bump structure. Moreparticularly, exemplary embodiments relate to an etching composition forpreventing and/or reducing impurities from being generated on aconductive bump, and a method of forming a bump structure using thesame.

2. Description of the Related Art

Generally, a conductive bump is employed for electrically connecting asemiconductor chip with electronic equipment. An electrical die sorting(EDS) process may be performed to examine the performance of thesemiconductor chip on which the conductive bump is formed. EDS processesmeasure electrical characteristics of the semiconductor chip on whichthe conductive bump is formed using a probe station to confirm whetherthe semiconductor chip has defects. The probe station includes a probecard for inputting/outputting an electrical signal through a probe tip,which directly makes contact with the conductive bump. The probe cardanalyzes the electrical signal to detect the defects of thesemiconductor chip on which the conductive bump is formed.

A conductive bump may be formed using an electroplating solution and anelectroplating process. The electroplating solution may include acompound having a cyano group or a compound without a cyano group.Lately, an electroplating solution including a compound without a cyanogroup, such as sodium gold sulfite (Na₃Au(SO₃)₂), has been more widelyused than an electroplating solution including a compound having a cyanogroup, such as potassium gold cyanide (KAu(CN)₂). As a result, a toxicgas such as hydrogen cyanide (HCN) is not generated during a subsequentprocess. Further, the conductive bump has a denser structure.

However, when the conductive bump is formed using a compound without thecyano group, impurities may remain on the conductive bump. Suchimpurities may cause a process error during an EDS process. Moreparticularly, when an under-bump metallurgy (UBM) layer exposed by theconductive bump is etched, impurities may be generated and the generatedimpurities may attach to a probe tip and cause an error in the analysisof an electrical signal. The impurities may include metal impuritiessuch as aluminum (Al) from a pad or titanium (Ti) from the UBM layer,polyimide or silicon oxynitride (SiON) from a passivation layer, oroxide impurities such as aluminum oxide or titanium oxide. As a resultof such impurities, although a semiconductor chip may be appropriatelyperformed, the probe station may output inappropriate results indicatingan electrical short or an electrical open circuit in the semiconductorchip.

In view of the foregoing, a cleaning process may be performed to removethe impurities from tip(s) of a probe card before and/or after an EDSprocess. However, cleaning processes may be abrasive and may damage theprobe tip. Thus, productivity may be reduced. Further, such cleaningprocesses may not sufficiently remove the impurities from a probe tip.Thus, a method(s) capable of preventing generation of the impurities isdesired.

SUMMARY

Embodiments are therefore directed to an etching composition for an UBMlayer that may substantially and/or completely overcome one or moreproblems due to limitations and disadvantages of the related art.

Exemplary embodiments provide an etching composition for an UBM layerthat may reduce and/or prevent impurities that may result duringformation of a bump structure from a conductive bump.

Exemplary embodiments provide an etching composition for an UBM layerthat may improve reliability of EDS processes by reducing and/orpreventing impurities that may attach to a probe tip of a probe card.

Exemplary embodiments provide a method of forming a bump structure usingan etching composition that results in relatively fewer impurities on aconductive bump that may attach to a probe card and cause errors in theanalysis of an electrical signal being analyzed therewith.

Exemplary embodiments to provide an etching composition for etching anUBM layer that may form a protective layer on a conductive bump toprevent and/or reduce etching residue or impurities that may begenerated during formation of the conductive bump from attaching to theconductive bump.

Exemplary embodiments provide an etching composition for etching an UBMlayer that may efficiently remove etching residue or impurities, whichmay be generated during formation of a conductive bump, from theconductive bump without damaging a polyimide layer, and aluminum layerand/or a silicon oxynitride layer.

Exemplary embodiments provide an etching composition for etching an UBMlayer that may result in relatively fewer and/or no impurities, whichmay result during formation of a conductive bump, and may preventimpurities from attaching to a probe card during an EDS process andincreasing a contact resistance.

Exemplary embodiments provide an etching composition that may reduce afrequency of a cleaning process for cleaning a probe tip due toimpurities, which may be generated during formation of a conductivebump, and may improve productivity.

At least one of exemplary embodiments may be realized by providing anetching composition for an under-bump metallurgy (UBM) layer includingabout 40% by weight to about 90% by weight of hydrogen peroxide (H₂O₂),about 1% by weight to about 20% by weight of an aqueous basic solutionincluding ammonium hydroxide (NH₄OH) or tetraalkylammonium hydroxide,about 0.01% by weight to about 10% by weight of an alcohol compound, andabout 2% by weight to about 30% by weight of an ethylenediamine-basedchelating agent.

The etching composition may include about 68% by weight to about 77% byweight of hydrogen peroxide, about 7% by weight to about 14% by weightof the aqueous basic solution including ammonium hydroxide, about 0.1%by weight to about 3% by weight of the alcohol compound, and about 15%by weight to about 20% by weight of the ethylenediamine-based chelatingagent, and the UBM layer includes titanium (Ti).

A weight ratio of the aqueous basic solution including ammoniumhydroxide to hydrogen peroxide may be in a range of about 1:6 to about1:9.

The etching composition may include about 75% by weight to about 83% byweight of hydrogen peroxide, about 1% by weight to about 7% by weight ofthe aqueous basic solution including tetraalkylammonium hydroxide, about0.01% by weight to about 3% by weight of the alcohol compound, and about15% by weight to about 20% by weight of the ethylenediamine-basedchelating agent, and the UBM layer includes titanium tungsten (TiW).

The etching composition may include about 1 ppm to about 1,000 ppm of anonionic surfactant. The nonionic surfactant may include a copolymer ofpolyethylene oxide and polypropylene oxide, or a block copolymer ofpolyethylene glycol and polypropylene glycol.

The aqueous basic solution may include about 25% by weight to about 50%by weight of ammonium hydroxide. The aqueous basic solution may includeabout 15% by weight to about 35% by weight of tetraalkylammoniumhydroxide. The ethylenediamine-based chelating agent may includeethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic aciddipotassium salt (EDTA-2K), ethylenediaminetetraacetic acid disodiumsalt (EDTA-2Na), or ethylenediaminetetraacetic acid tetrasodium salt(EDTA-4Na).

At least one of exemplary embodiments may be realized by providing amethod of forming a bump structure, including forming a pad electricallyconnected to a semiconductor chip on a substrate, forming a passivationlayer pattern on the substrate that exposes the pad, forming anunder-bump metallurgy (UBM) layer on the passivation layer pattern andon the pad exposed by the passivation layer pattern, forming aconductive bump on the UBM layer, and removing a portion of the UBMlayer using the conductive bump as a mask with an etching compositionincluding about 40% by weight to about 90% by weight of hydrogenperoxide (H₂O₂), about 1% by weight to about 20% by weight of an aqueousbasic solution including ammonium hydroxide (NH₄OH) ortetraalkylammonium hydroxide, about 0.01% by weight to about 10% byweight of an alcohol compound, and about 2% by weight to about 30% byweight of an ethylenediamine-based chelating agent.

Removing the portion of the UBM layer may include etching the UBM layerusing the etching composition at a temperature of about 40° C. to about70° C. for about 1 minute to about 5 minutes.

After removing the UBM layer, the method may include performing a heattreatment on the substrate on which the conductive bump is formed.

After performing the heat treatment, the method may include cleaning thebump structure using the etching composition at a temperature of about20° C. to about 40° C. for about 30 seconds to about 1 minute.

The UBM layer may include at least one of titanium tungsten (TiW),chromium (Cr), copper (Cu), titanium (Ti), nickel (Ni), nickel vanadium(NiV), palladium (Pd), chromium/copper (Cr/Cu), titanium tungsten/copper(TiW/Cu), titanium tungsten/gold (TiW/Ag) and nickel vanadium/copper(NiV/Cu) and mixtures thereof.

The pad may include aluminum and the passivation layer may include atleast one of polyimide or silicon oxynitride.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will become more apparent to those of ordinaryskill in the art by describing in detail exemplary embodiments withreference to the attached drawings, in which:

FIGS. 1, 2, 3, 4, 5, 6 and 7 illustrate cross-sectional views of stagesin an exemplary method of forming a bump structure according to anexemplary embodiment;

FIG. 8 illustrates a graph of cleaning properties of an etchingcomposition with regard to titanium (Ti) according to a content of anaqueous basic solution including ammonium hydroxide; and

FIG. 9 illustrates a graph of cleaning properties of an etchingcomposition with regard to titanium (Ti) according to a content of anethylenediamine-based chelating agent.

DETAILED DESCRIPTION

Korean Patent Application Nos. 2007-119639, filed on Nov. 22, 2007, and2008-92821, filed on Sep. 22, 2008, in the Korean Intellectual PropertyOffice, are incorporated by reference herein in their entirety.

Exemplary embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” another element or layer, it can be directlyon or connected to the other element or layer or intervening elements orlayers may be present. In contrast, when an element is referred to asbeing “directly on,” “directly connected to” another element or layer,there are no intervening elements or layers present. Like numerals referto like elements throughout the specification. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

The terminology used herein is for the purpose of describing particularexemplary embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

As used herein, the expressions “at least one” and “and/or” areopen-ended expressions that are both conjunctive and disjunctive inoperation. For example, each of the expressions “at least one of A, B,and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” and“A, B, and/or C” includes the following meanings: A alone; B alone; Calone; both A and B together; both A and C together; both B and Ctogether; and all three of A, B, and C together. Further, theseexpressions are open-ended, unless expressly designated to the contraryby their combination with the term “consisting of.” For example, theexpression “at least one of A, B, and C” may also include an nth member,where n is greater than 3, whereas the expression “at least one selectedfrom the group consisting of A, B, and C” does not.

Exemplary embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized exemplary embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. Thus, the regions illustrated in the figures areschematic in nature and their shapes are not intended to illustrate theactual shape of a region of a device and are not intended to limit thescope of the present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

An exemplary etching composition for an under-bump metallurgy (UBM)layer will be described below.

An etching composition for a UBM layer may include about 40% by weightto about 90% by weight of hydrogen peroxide (H₂O₂), about 1% by weightto about 20% by weight of an aqueous basic solution including ammoniumhydroxide (NH₄OH) or tetraalkylammonium hydroxide, about 0.01% by weightto about 10% by weight of an alcohol compound and about 2% by weight toabout 30% by weight of an ethylenediamine-based chelating agent. Theetching composition may further include a nonionic surfactant as anadditive. The UBM layer may be formed using, e.g., titanium (Ti) ortitanium tungsten (TiW).

Hydrogen peroxide included in the etching composition may effectivelydissolve impurities. In exemplary embodiments, hydrogen peroxide mayoxidize impurities including titanium (Ti), titanium oxide (TiO_(x)),tungsten (W), tungsten oxide (WO_(y)) and/or organic impurities, whichmay remain on a conductive bump and a UBM layer pattern under theconductive bump. Hydrogen peroxide may form a thin oxide layer on theconductive bump. The thin oxide layer may prevent and/or reduce adhesionof impurities generated by an etching process on the conductive bump.

When the etching composition includes less than about 40% by weight ofhydrogen peroxide based on a total weight of the etching composition,impurities may not be effectively removed from the conductive bump andthe UBM layer pattern. When the etching composition includes more thanabout 90% by weight of hydrogen peroxide, the UBM layer patternresulting from etching of the UBM layer, may be excessively oxidized byhydrogen peroxide and may be damaged. Therefore, in embodiments, theetching composition may include about 40% by weight to about 90% byweight of hydrogen peroxide.

The aqueous basic solution including ammonium hydroxide may removetitanium included in the UBM layer and may dissolve impurities, e.g.,titanium, titanium oxide and/or the organic impurities, which may remainon the conductive bump. In exemplary embodiments, the aqueous basicsolution including ammonium hydroxide may include about 25% by weight toabout 50% by weight of ammonium hydroxide.

The aqueous basic solution including tetraalkylammonium hydroxide mayremove titanium tungsten included in the UBM layer and may dissolveimpurities, e.g., titanium, tungsten, titanium oxide, tungsten oxideand/or the organic impurities that may remain on the conductive bump. Inexemplary embodiments, the aqueous basic solution includingtetraalkylammonium hydroxide may include about 15% by weight to about35% by weight of tetraalkylammonium hydroxide.

When the etching composition includes less than about 1% by weight ofthe aqueous basic solution including ammonium hydroxide ortetraalkylammonium hydroxide based on the total weight of the etchingcomposition, impurities may not be effectively removed from theconductive bump. When the etching composition includes more than about20% by weight of the aqueous basic solution including ammonium hydroxideor tetraalkylammonium hydroxide, the UBM layer pattern includingtitanium or titanium tungsten may be eroded by the etching compositionand may damage the conductive bump. Thus, in embodiments, the etchingcomposition may include about 1% by weight to about 20% by weight of theaqueous basic solution including ammonium hydroxide ortetraalkylammonium hydroxide.

In exemplary embodiments, a weight ratio of the aqueous basic solutionincluding ammonium hydroxide to the hydrogen peroxide may affect anetching rate of titanium included in the UBM layer and may cause damageto a pad including aluminum. When the weight ratio of hydrogen peroxidewith respect to the aqueous basic solution including ammonium hydroxideis less than about 6, the pad including aluminum may be damaged and theetching rate of titanium may be reduced. When the weight ratio ofhydrogen peroxide with respect to the aqueous basic solution includingammonium hydroxide is more than about 9, the etching rate of the UBMlayer may be increased. However, aluminum included in the pad may beetched with titanium included in the UBM layer. Thus, the weight ratioof the aqueous basic solution including ammonium hydroxide to hydrogenperoxide may be about 1:6 to about 1:9.

The alcohol compound included in the etching composition may removeorganic impurities generated while the conductive bump is formed by anelectroplating process.

In exemplary embodiments, the alcohol compound included in the etchingcomposition may include a C₁-C₄ monoalcohol, a C₁-C₄ diol, a C₁-C₆aminoalcohol, etc. These may be used alone or in a mixture thereof. Forexample, the alcohol compound may include methanol, ethanol, propanol,butanol, ethyleneglycol, propanediol, butanediol, monoethanolamine,diethanolamine, triethanolamine, propanolamine, etc.

When the etching composition includes less than about 0.01% by weight ofthe alcohol compound, the organic impurities may remain on theconductive bump after etching the UBM layer. Further, the metal, e.g.,titanium or titanium tungsten, in the UBM layer pattern under theconductive bump may be etched. When the etching composition includesmore than about 10% by weight of the alcohol compound, removalefficiency of the organic impurities may not improve compared to that ofthe etching composition including about 10% by weight of the alcoholcompound, and the amount of the metal, e.g., titanium, remaining on theconductive bump may be higher. Thus, in embodiments, the etchingcomposition may include about 0.01% by weight to about 10% by weight ofthe alcohol compound.

The ethylenediamine-based chelating agent included in the etchingcomposition may prevent a metal ion, e.g., a titanium ion, which may begenerated during the etching process from reacting with an oxidant,e.g., hydrogen peroxide, and forming a metal oxide, e.g., titaniumoxide. The ethylenediamine-based chelating agent may react with a metalion, e.g., titanium ion, to form a stable chelate compound.

In exemplary embodiments, the ethylenediamine-based chelating agent mayinclude ethylenediaminetetraacetic acid (EDTA),ethylenediaminetetraacetic acid dipotassium salt (EDTA-2K),ethylenediaminetetraacetic acid disodium salt (EDTA-2Na),ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na), etc. Forexample, the ethylenediamine-based chelating agent may beethylenediaminetetraacetic acid dipotassium salt (EDTA-2K).

When the etching composition includes less than about 2% by weight ofthe ethylenediamine-based chelating agent, the metal ion, e.g., thetitanium ion, which may be generated during the etching process, may notreact with the ethylenediamine-based chelating agent and may not form astable chelate compound. When the etching composition includes more thanabout 30% by weight of the ethylenediamine-based chelating agent, anamount of the ethylenediamine-based chelating agent may be more thanthat of the metal ion that may be generated during the etching processof the UBM layer. Thus, an excess of the ethylenediamine-based chelatingagent may not react with the metal ion. As a result, theethylenediamine-based chelating agent may remain on the conductive bump.Thus, in embodiments, the etching composition may include about 2% byweight to about 30% by weight of the ethylenediamine-based chelatingagent.

The etching composition may further include an additive. The additivemay include about 1 ppm to about 1,000 ppm of a nonionic surfactant. Thenonionic surfactant may dissolve impurities, e.g., the metal such astitanium, the metal oxide such as the titanium oxide or tungsten oxide,the organic impurities, so that the etching composition may permeateinto the impurities attached to the conductive bump. Thus, removalefficiency of the impurities may be enhanced.

In exemplary embodiments, the nonionic surfactant may include acopolymer of polyethylene oxide and polypropylene oxide or a blockcopolymer of polyethylene glycol and polypropylene glycol. For example,the nonionic surfactant may include NCW (trade name; manufactured byWako Pure Chemical Industries, Ltd. in Japan) or Synperonic PE/F68,Synperonic PE/L61 or Synperonic PE/L64 (trade names; manufactured byFluka Chemie GmBH in Germany).

When the etching composition includes less than about 1 ppm of thenonionic surfactant, the etching composition may not easily permeateinto the impurities attached to the conductive bump, so that the removalefficiency of the impurities may be reduced. When the etchingcomposition includes more than about 1,000 ppm of the nonionicsurfactant, the removal efficiency of the impurities may not besubstantially improved and the nonionic surfactant may remain on theconductive bump after the etching process of the UBM layer. Thus, theetching composition may further include about 1 ppm to about 1,000 ppmof the nonionic surfactant.

In exemplary embodiments, when the UBM layer includes titanium, theetching composition may include about 68% by weight to about 77% byweight of hydrogen peroxide, about 7% by weight to about 14% by weightof the aqueous basic solution including ammonium hydroxide, about 0.1%by weight to about 3% by weight of the alcohol compound, and about 15%by weight to about 20% by weight of the ethylenediamine-based chelatingagent. The etching composition may further include about 1 ppm to about1,000 ppm of the nonionic surfactant as the additive.

In exemplary embodiments, when the UBM layer includes titanium tungsten,the etching composition may include about 75% by weight to about 83% byweight of hydrogen peroxide, about 1% by weight to about 7% by weight ofthe aqueous basic solution including tetraalkylammonium hydroxide, about0.01% by weight to about 3% by weight of the alcohol compound, and about15% by weight to about 20% by weight of the ethylenediamine-basedchelating agent. The etching composition may further include about 1 ppmto about 1,000 ppm of the nonionic surfactant as the additive.

According to exemplary embodiments, the etching composition describedabove for the UBM layer may effectively remove the impurities generatedin the etching process of the UBM layer exposed by the conductive bump.The etching composition may suppress and/or reduce damage to a polyimidelayer or a silicon oxynitride layer serving as a passivation layer or analuminum layer, which may serve as a fuse, during the etching process ofthe UBM layer. By employing the etching composition includingcharacteristics described above, relatively fewer and/or no impuritiesmay remain on the conductive bump that may be brought into contact witha probe card. Thus, by employing the etching composition described aboveand reducing and/or eliminating the impurities on the conductive bump,it may be possible to prevent and/or reduce an increase in contactresistance during an electrical die sorting (EDS) process. Thus, afailure that may result during a performance test of the semiconductordevice as a result of such impurities may be prevented and/or reduced,and reliability of the performance test(s) may be improved.

Hereinafter, a method of forming a bump structure according to exemplaryembodiments will be explained in detail with reference to theaccompanying drawings.

According to exemplary embodiments, a bump structure may be manufacturedby forming a conductive bump on a substrate including a semiconductorchip, e.g., an LCD driver integrated circuit (LDI) chip. The bumpstructure(s) may be formed by, e.g., etching the UBM layer includingtitanium (Ti) or titanium tungsten (TiW) using the etching compositionin accordance with exemplary embodiments. More particularly, e.g., anLDI chip may include a plurality of conductive bumps that play a role inthe operation of the LDI chip. As conductive bumps generally play a rolein the operation of a chip, characteristics of the conductive bump(s) ona semiconductor chip are important.

Hereinafter, an exemplary method of forming a bump structure will bedescribed with reference to FIGS. 1 to 7. FIGS. 1 to 7 illustratecross-sectional views of stages in an exemplary method of forming thebump structure.

Referring to FIG. 1, a pad 110 may be formed on a substrate 100. Varioussemiconductor structures (not illustrated) may be formed on thesubstrate 100 and the pad 110 may be electrically connected with thesemiconductor structures. The pad 110 may serve as a contactelectrically connecting the semiconductor structures formed on thesubstrate 100 with a structure formed on the pad 110. The pad 110 may beformed using a conductive material. In exemplary embodiments, the pad110 may be formed using aluminum or copper.

A passivation layer pattern 120 exposing the pad 110 may be formed onthe pad 110. The passivation layer pattern 120 may protect thesemiconductor structure formed on the substrate 100. The passivationlayer pattern 120 may include an opening 101 exposing the pad 110. Theopening 101 may be formed by a photolithography process using a mask. Inexemplary embodiments, the passivation layer pattern 120 may include,e.g., polyimide, silicon oxynitride, etc.

In exemplary embodiments, the passivation layer pattern 120 may includea first passivation layer pattern 120 a and a second passivation layerpattern 120 b. More particularly, a first passivation layer (notillustrated) may be formed on the pad 110 and a second passivation layer(not illustrated) may be formed on the first passivation layer. Aphotolithography process may be performed on the first and the secondpassivation layers to form the passivation layer pattern 120 includingthe first passivation layer pattern 120 a and the second passivationlayer pattern 120 b on the pad 110.

Referring to FIG. 2, a UBM layer 130 may be formed on the pad 110. Moreparticularly, the UBM layer 130 may be formed on the passivation layerpattern 120 and on a portion of the pad 110 exposed by the opening 101in the passivation layer pattern 120. Since a conductive bump (150, seeFIG. 5) may not be directly formed on the pad 110, the UBM layer 130 maybe formed on the pad 110 and the conductive bump 150 may be formed onthe UBM layer 130. The UBM layer 130 may be formed using a materialhaving high adhesive properties with the passivation layer pattern 120,having a low resistance with regard to the pad 110 and capable ofreducing stress on the substrate 100. In exemplary embodiments, the UBMlayer 130 may be formed using titanium (Ti), tungsten (W), chromium(Cr), copper (Cu), nickel (Ni), nickel vanadium (NiV), palladium (Pd),chromium/copper (Cr/Cu), titanium tungsten/copper (TiW/Cu), titaniumtungsten/gold (TiW/Au), nickel vanadium/copper (NiV/Cu), etc. These maybe used alone or in a mixture thereof. In exemplary embodiments, the UBMlayer 130 may be formed, e.g., by an evaporation process, a sputteringprocess, an electroplating process or an electroless plating process.For example, the UBM layer 130 may be formed by sequentially depositinggold (Ag) and titanium tungsten (TiW) using a sputtering process. Insuch embodiments, a titanium tungsten layer may serve as a diffusionprevention layer between pad 110 and an upper wiring formed in asubsequent process. More particularly, e.g., a gold layer may improveadhesive properties between the pad 110 and the conductive bump 150 andmay serve as a seed layer in an electroplating process used for formingthe upper wiring.

Referring to FIG. 3, a photoresist film 140 may be formed on the UBMlayer 130. In exemplary embodiments, the photoresist film 140 may beformed by a spin-coating process, a roll-coating process or aslit-coating process. The photoresist film 140 may prevent a currentfrom being transmitted to the UBM layer 130 so the UBM layer 130 may notbe electroplated in the electroplating process. More particularly, thephotoresist film 140 may be patterned to expose a portion of the UBMlayer 130 where the conductive bump 150 may be formed. In suchembodiments, the photoresist film 140 may prevent a current from beingtransmitted to a portion(s) of the UBM layer 130 covered by thephotoresist film 140, while a current may flow to a portion of the UBMlayer 130 not covered by the photoresist film 140, e.g., the portionsubstantially corresponding to where the conductive bump 150 may beformed.

More particularly, referring to FIG. 4, the photoresist film 140 may bepatterned to form a photoresist pattern 142. The photoresist pattern 142may define the region where the conductive bump 150 may be formed on theUBM layer 130. The photoresist pattern 142 may be formed by aphotolithography process. The region on which the conductive bump 150 isformed may be over the pad 110. In embodiments, after the photoresistpattern 142 is formed, a plasma ashing process may be further performedto remove residue generated during formation of the photoresist pattern142 from the UBM layer 130.

Referring to FIG. 5, the conductive bump 150 may be formed on theportion of the UBM layer 130 exposed by the photoresist pattern 142. Theconductive bump 150 may have, e.g., a line shape or bar shape. Inembodiments, the conductive bump 150 may be formed by the electroplatingprocess. The electroplating process may be performed on the UBM layer130 using the photoresist pattern 142 as a plating mask to form theconductive bump 150. In exemplary embodiments, the conductive bump 150may be formed using an electroplating solution including a compoundwithout a cyano group, e.g., sodium gold sulfite (Na₃Au(SO₃)₂).

Referring to FIG. 6, the photoresist pattern 142 may be removed from theUBM layer 130. The photoresist pattern 142 may be removed by an ashingprocess and/or a stripping process.

Referring to FIG. 7, the portion of the UBM layer 130 exposed by theconductive bump 150 may be etched using an etching composition and theconductive bump 150 as an etching mask to form a UBM layer pattern 132.A bump structure 200 including the pad 110, the passivation layerpattern 120, the UBM layer pattern 132 and the conductive bump 150 maybe formed on the substrate 100.

The etching composition for the UBM layer 130 may include about 40% byweight to about 90% by weight of hydrogen peroxide (H₂O₂) as an oxidant,about 1% by weight to about 20% by weight of an aqueous basic solutionincluding ammonium hydroxide (NH₄OH) or tetraalkylammonium hydroxide,about 0.01% by weight to about 10% by weight of an alcohol compound, andabout 2% by weight to about 30% by weight of an ethylenediamine-basedchelating agent. In exemplary embodiments, the etching composition mayfurther include about 1 ppm to about 1,000 ppm of a nonionic surfactant.

Hydrogen peroxide may effectively dissolve oxidizing impuritiesincluding titanium (Ti), titanium oxide (TiO_(x)), tungsten (W),tungsten oxide (WO_(y)) or organic impurities that may remain on theconductive bump 150 and the UBM layer pattern 132. The aqueous basicsolution including ammonium hydroxide or tetraalkylammonium hydroxidemay remove titanium included in the UBM layer 130 and may dissolve theimpurities, e.g., titanium, titanium oxide, aluminum (Al), aluminumoxide (AlO_(x)), the organic impurities, which may remain on theconductive bump 150. The alcohol compound may remove the organicimpurities remaining on the conductive bump 150. Theethylenediamine-based chelating agent may prevent a metal ion, e.g., atitanium ion generated in the etching process, from reacting with theoxidant such as hydrogen peroxide and forming a metal oxide such astitanium oxide. The ethylenediamine-based chelating agent may react withthe metal ion to form a chelate compound. In exemplary embodiments, aweight ratio of the aqueous basic solution including ammonium hydroxideto hydrogen peroxide may be in a range of about 1:6 to about 1:9. Such aratio may prevent and/or reduce damage to the pad 110 that may include,e.g., aluminum, and/or improve an etching rate of the UBM layer 130.

More particularly, e.g., in one exemplary embodiment in which the UBMlayer 130 includes, e.g., titanium, the UBM layer 130 may be etchedusing the etching composition including about 68% by weight to about 77%by weight of hydrogen peroxide, about 7% by weight to about 14% byweight of the aqueous basic solution including ammonium hydroxide, about0.1% by weight to about 3% by weight of the alcohol compound, and about15% by weight to about 20% by weight of the ethylenediamine-basedchelating agent. The etching composition for the UBM layer 130 includingtitanium may further include about 1 ppm to about 1,000 ppm of thenonionic surfactant.

In another exemplary embodiment in which the UBM layer 130 includes,e.g., titanium tungsten, the UBM layer 130 may be etched using theetching composition including about 75% by weight to about 83% by weightof hydrogen peroxide, about 1% by weight to about 7% by weight of theaqueous basic solution including tetraalkylammonium hydroxide, about0.01% by weight to about 3% by weight of the alcohol compound, and about15% by weight to about 20% by weight of the ethylenediamine-basedchelating agent. The etching composition for the UBM layer 130 includingtitanium tungsten may further include about 1 ppm to about 1,000 ppm ofthe nonionic surfactant.

The UBM layer 130 may be etched by immersing the substrate 100 in theetching composition. For example, the substrate 100 may be immersed inthe etching composition at a temperature of about 40° C. to about 70° C.for about 1 minute to about 5 minutes.

In exemplary embodiments, after the UBM layer 130 exposed by theconductive bump 150 is etched using the etching composition, a heattreatment may be further performed on the substrate 100 on which thebump structure(s) 200 is formed. For example, the heat treatment may beperformed at a temperature of about 250° C. to about 360° C. under anoxygen atmosphere or a nitrogen atmosphere.

In exemplary embodiments, after the heat treatment is performed on thesubstrate 100, a cleaning process may be further performed using theetching composition. For example, the cleaning process may be performedusing the etching composition at a temperature of about 20° C. to about40° C. for about 30 seconds to about 1 minute.

When the UBM layer is etched to form the bump structure(s) 200 using theetching composition, damage to the passivation layer pattern 120including, e.g., polyimide or silicon oxynitride, and the pad 110 or afuse including, e.g., aluminum may be reduced and/or suppressed. Theimpurities including, e.g., titanium, titanium oxide, tungsten, tungstenoxide, organic impurities, etc. may be effectively removed from the bumpstructure(s) 200. When an EDS process is performed on the bumpstructure(s) 200 during a subsequent process, a probe tip may not becontaminated or may be relatively less contaminated by the impurities.Thus, abrasion of the probe tip due to a cleaning process for cleaning acontaminated probe card may be prevented and/or reduced. That is, byreducing and/or eliminating contamination of the probe card by theimpurities that may remain on the conductive bump(s) as a result ofetching the UBM layer 130, a frequency of the cleaning process may bedecreased and reliability of EDS processing and/or productivity may beimproved.

Exemplary embodiments will be described below through Examples andComparative Examples. It is understood that various changes andmodifications may be made by one ordinary skilled in the art resultingin embodiments other than the examples set forth below.

Preparation of exemplary etching compositions for etching an UBM layerwill be described below.

Example 1

A solution including about 79.49% by weight of hydrogen peroxide (H₂O₂),about 3% by weight of an aqueous basic solution includingtetramethylammonium hydroxide (TMAH), about 0.5% by weight ofethyleneglycol (EG), about 17% by weight of ethylenediaminetetraaceticacid dipotassium salt (EDTA-2K) and about 0.01% by weight of a nonionicsurfactant NCW (trade name; manufactured by Wako Pure ChemicalIndustries, Ltd. in Japan) was prepared. The solution was stirred forabout 30 minutes to prepare an etching composition for the UBM layer.The aqueous basic solution containing tetramethylammonium hydroxideincluded about 25% by weight of tetramethylammonium hydroxide.

Example 2

An etching composition was prepared by performing processessubstantially the same as that of Example 1 except using about 72.49% byweight of hydrogen peroxide about 10% by weight of an aqueous basicsolution including ammonium hydroxide (NH₄OH). The aqueous basicsolution containing ammonium hydroxide included about 38% by weight ofammonium hydroxide.

Comparative Example 1

A solution including about 100% by weight of hydrogen peroxide wasprepared. The solution was stirred for about 30 minutes to prepare anetching composition.

Comparative Example 2

A solution including about 100% by weight of a diluted hydrogen fluoride(DHF) prepared. The solution was stirred for about 30 minutes to preparean etching composition. A weight ratio between water and hydrogenfluoride in the diluted hydrogen fluoride was about 200:1.

Comparative Example 3

An etching composition was prepared by processes substantially the sameas that of Example 1 except that about 80% by weight of hydrogenperoxide was used and no NCW and ethyleneglycol (EG) were added.

Comparative Example 4

An etching composition was prepared by processes substantially the sameas that of Example 1 except that about 79.99% by weight of hydrogenperoxide was used and no ethyleneglycol (EG) was added.

Comparative Example 5

An etching composition was prepared by processes substantially the sameas those of Example 2 except that about 73% by weight of hydrogenperoxide was used and no NCW and ethyleneglycol (EG) were added.

Ingredients of the etching compositions according to Examples 1 and 2and Comparative Examples 1 to 5 are described in the following Table 1.Contents of ingredients are represented by % by weight.

TABLE 1 Aqueous Basic Alcohol Chelating Oxidant Solution Compound AgentSurfactant H₂O₂ DHF TMAH NH₄OH EG EDTA-2K NCW Example 1 79.49 — 3 — 0.517 0.01 Example 2 72.49 — — 10 0.5 17 0.01 Comparative 100 — — — — — —Example 1 Comparative — 100 — — — — — Example 2 Comparative 80 — 3 — —17 — Example 3 Comparative 79.99 — 3 — — 17 0.01 Example 4 Comparative73 — — 10 — 17 — Example 5

[Experiment 1]

Evaluation of etching properties and cleaning properties of the etchingcompositions of Examples 1 and 2 and Comparative Examples 1 to 5.Substrates were prepared in order to evaluate of etching properties ofthe etching compositions according to Examples 1 and 2 and ComparativeExamples 1 to 5. A titanium (Ti) layer, a titanium tungsten (TiW) layer,an aluminum (Al) layer, a silicon oxynitride (SiON) layer and apolyimide layer were formed on each of the substrates, respectively. Thesubstrates were etched by immersing the substrates in the etchingcomposition according to the Examples 1 and 2 and Comparative Examples 1to 5, respectively, at a temperature of about 40° C. to about 70° C. forabout 1 minute to about 5 minutes. Each of the substrates was cleaned byimmersing the substrate in distilled water for about 5 minutes. Each ofthe substrates was then dried using argon gas or nitrogen gas. Surfacesof the substrates on which the aluminum layer, silicon oxynitride layerand the polyimide layer were formed, respectively, were observed using amicroscope to confirm whether the aluminum layer, the silicon oxynitridelayer and the polyimide layer were etched by the etching compositionsaccording to Examples 1 and 2 and Comparative Examples 1 to 5. Resultsare illustrated in the following Table 2.

TABLE 2 Aluminum Silicon Oxynitride Polyimide Layer Layer Layer Example1 ◯ ◯ ◯ Example 2 ◯ ◯ ◯ Comparative Example 1 ◯ ◯ ◯ Comparative Example2 X Δ Δ Comparative Example 3 ∘ ◯ ◯ Comparative Example 4 ◯ ◯ ◯Comparative Example 5 ◯ ◯ ◯

In Table 2, “O” denotes that the aluminum layer, the silicon oxynitridelayer or the polyimide layer was not etched by the etching compositions.“o” denotes that the aluminum layer, the silicon oxynitride layer or thepolyimide layer was etched a little. “Δ” denotes the aluminum layer, thesilicon oxynitride layer or the polyimide layer was etched by an averageamount. “X” denotes that the aluminum layer, the silicon oxynitridelayer or the polyimide layer was etched a lot.

Referring to Table 2, the etching compositions of Examples 1 and 2 didnot etch the aluminum layer, the silicon oxynitride layer and thepolyimide layer exposed to the etching compositions while forming a bumpstructure. Thus, it was confirmed that the etching compositionsaccording to Examples 1 and 2 etched the UBM layer without damaging thealuminum layer, the silicon oxynitride layer and the polyimide layer.

Evaluation of the etching properties with regard to the titanium layerand the titanium tungsten layer was performed using an automated visualinspection (AVI) system. Evaluation of cleaning properties with regardto an amount of titanium oxide remaining on the titanium layer and thetitanium tungsten layer was performed using a total reflection X-rayfluorescence (TXRF) spectrometer that measured a surface density ofatoms included in titanium oxide. An EDS sanding interval, i.e., anumber of chips examined without performing a cleaning process of aprobe tip being used, was measured using a reexamination rate of thechip. Results are illustrated in the following Table 3.

TABLE 3 Amount of Etching TiO_(x) Residue EDS Sanding IntervalProperties (E¹⁰ atoms/cm²) (number of chips) TiW Ti TiW Ti TiW TiExample 1 ◯ ◯ 0 1.16 1,939 1,871 Example 2 X ◯ — 0 — 1,763 Comparative ◯X 595.6 998.2 50 30 Example 1 Comparative — — — — — 433 Example 2Comparative ◯ Δ 0 187.4 1,100 510 Example 3 Comparative ◯ ◯ 0 12.4 1,300600 Example 4 Comparative X ◯ — 7.52 — 560 Example 5

In Table 3 “O”, “Δ” and “X” may be substantially the same as those ofTable 2 and “-” denotes that the results were not measured.

Referring to Table 3, as illustrated in the etching properties of theetching compositions according to Examples 1 and 2, the etchingcompositions of Examples 1 and 2 efficiently etched the titanium layer.The etching composition of Example 1 including the aqueous basicsolution containing tetramethylammonium hydroxide also effectivelyetched the titanium tungsten layer.

As illustrated in the evaluation of the amount of the titanium oxideresidue, the etching composition of Example 1 exhibited better cleaningproperties with regard to the titanium tungsten layer than the titaniumlayer. The etching composition of Example 2 including the aqueous basicsolution containing ammonium hydroxide had better cleaning propertiesthan the etching composition of Example 1 with regard to the titaniumlayer.

As illustrated in the EDS sanding interval, when the etchingcompositions of Examples 1 and 2 were used for etching the UBM layer,about 1,700 chips or more were examined using the probe tip withoutperforming the cleaning process of the probe tip. It was confirmed thatthe etching compositions of Examples 1 and 2 including both the alcoholcompound and the ethylenediamine-based chelating agent generated lessimpurities compared to the etching compositions of Comparative Examples3 and 4 without the alcohol compound or the ethylenediamine-basedchelating agent. The etching composition of Example 2 including thealcohol compound, the ethylenediamine-based chelating agent and theaqueous basic solution containing ammonium hydroxide had superiorcleaning properties for efficiently removing titanium from thesubstrate. When the etching composition of Example 2 was used, about1,763 chips were examined during the EDS process without performing acleaning process for cleaning the probe tip because no titanium oxideresidue was measured as remaining on the conductive bump, i.e., the TXRFspectrometer didn't detect a surface density of atoms included intitanium oxide.

[Experiment 2]

FIG. 8 illustrates a graph of cleaning properties of an etchingcomposition with regard to titanium according to a content of an aqueousbasic solution including ammonium hydroxide (NH₄OH).

The cleaning properties of the etching composition was evaluated basedon an amount of titanium residue remaining on a conductive bump afteretching a UBM layer. The cleaning properties of the etching compositionwas evaluated based on an EDS sanding interval, i.e., the number ofchips examined using a probe tip without performing a cleaning processof the probe tip. The amount of the titanium residue and the number ofchips were measured using substantially the same methods as those ofExperiment 1. In FIG. 8, “I” represents the amount of the titaniumresidue and “II” represents the EDS sanding interval, that is, thenumber of chips examined during an EDS process using the probe tipwithout performing a cleaning process of the probe tip.

In order to evaluate the cleaning properties of the etching compositionaccording to exemplary embodiments, etching compositions were prepared.All the etching compositions included about 0.5% by weight of an alcoholcompound, and about 15% by weight of ethylenediaminetetraacetic aciddipotassium salt (EDTA-2K). Each of the etching compositions includedabout 0% by weight, about 5% by weight, about 10% by weight, about 12%by weight and about 15% by weight of the aqueous basic solutionincluding ammonium hydroxide , respectively, and a remainder of hydrogenperoxide (H₂O₂), respectively, based on the total amount of the etchingcompositions.

Referring to FIG. 8, when the etching composition included more thanabout 5% by weight of the aqueous basic solution including ammoniumhydroxide, the titanium residue did not remain on the conductive bumpafter etching the UBM layer using the etching composition. Asillustrated in FIG. 8, when the etching composition included about 12%by weight of the aqueous basic solution including ammonium hydroxide,about 2,000 chips were examined using the probe tip without performingthe cleaning process of the probe tip. Thus, when the etchingcomposition includes about 15% by weight of ethylenediaminetetraaceticacid dipotassium salt, the etching composition may include about 12% byweight of the aqueous basic solution including ammonium hydroxide.

[Experiment 3]

FIG. 9 illustrates a graph illustrating of cleaning properties of anetching composition with regard to titanium according to a content of anethylenediamine-based chelating agent.

The cleaning properties of the etching composition was evaluated basedon an amount of titanium residue remaining on a conductive bump afteretching a UBM layer. The cleaning properties of the etching compositionwas evaluated based on an EDS sanding interval, that is, a number ofchips examined using a probe tip without performing a cleaning processof the probe tip. The amount of the titanium residue and the number ofchips were measured performing processes substantially the same as thoseof Experiment 1. In FIG. 9, “III” represents the amount of the titaniumresidue and “IV” represents the EDS sanding interval, that is, thenumber of chips examined using the probe tip without performing acleaning process of the probe tip during an EDS process.

In order to evaluate the cleaning properties of the etching compositionaccording to exemplary embodiments, etching compositions were prepared.All the etching compositions included about 0.5% by weight of an alcoholcompound, and about 12% by weight of an aqueous basic solution includingammonium hydroxide (NH₄OH). Each of the etching compositions includedabout 0% by weight, about 5% by weight, about 10% by weight, about 12%by weight and about 15% by weight of ethylenediaminetetraacetic aciddipotassium salt (EDTA-2K), respectively, and a remainder of hydrogenperoxide (H₂O₂), respectively, based on the total amount of the etchingcompositions.

Referring to FIG. 9, when the etching composition did not includeethylenediaminetetraacetic acid dipotassium salt (EDTA-2K), i.e., 0% byweight, the titanium residue did not remain on the conductive bump afteretching the UBM layer using the etching composition. As the content ofethylenediaminetetraacetic acid dipotassium salt was increased fromabout 0% by weight to about 15% by weight, the EDS sanding interval,i.e., a number of chips examined using the probe tip was increasedwithout performing the cleaning process of the probe tip. Thus, thecleaning properties of the etching composition increased in proportionto the content of the ethylenediamine-based chelating agent of about 0%by weight to about 15% by weight.

The etching compositions may efficiently etch the titanium layer andtitanium tungsten layer without damaging the aluminum layer, siliconoxynitride layer and the polyimide layer. Further, the etchingcompositions may remove the impurities including titanium oxide. Thus,etching compositions according to properties described above may preventand/or reduce contamination of a probe tip used for the EDS process.

According to embodiments, an etching composition may efficiently removea UBM layer and impurities without damaging layers adjacent to the UBMlayer and may reduce and/or prevent adhesion of impurities on aconductive bump that may result from etching the UBM layer when formingthe conductive bump. Thus, the impurities may not be attached to a probecard during an EDS process and may prevent a contact resistance fromincreasing. Further, a frequency of a cleaning process of a probe tipmay be reduced to improve productivity.

Exemplary embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation.Accordingly, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made without departingfrom the spirit and scope of the present invention as set forth in thefollowing claims.

1.-9. (canceled)
 10. A method of forming a bump structure, comprising:forming a pad electrically connected to a semiconductor chip on asubstrate; forming a passivation layer pattern on the substrate, thepassivation layer pattern exposing the pad; forming an under-bumpmetallurgy (UBM) layer on the passivation layer pattern and on the padexposed by the passivation layer pattern; forming a conductive bump onthe UBM layer; and removing a portion of the UBM layer using theconductive bump as a mask with an etching composition including about40% by weight to about 90% by weight of hydrogen peroxide (H₂O₂), about1% by weight to about 20% by weight of an aqueous basic solutionincluding ammonium hydroxide (NH₄OH) or tetraalkylammonium hydroxide,about 0.01% by weight to about 10% by weight of an alcohol compound, andabout 2% by weight to about 30% by weight of an ethylenediamine-basedchelating agent.
 11. The method as claimed in claim 10, wherein a weightratio of the aqueous basic solution including ammonium hydroxide tohydrogen peroxide is in a range of about 1:6 to about 1:9.
 12. Themethod as claimed in claim 10, wherein the etching composition comprisesabout 68% by weight to about 77% by weight of hydrogen peroxide, about7% by weight to about 14% by weight of the aqueous basic solutionincluding ammonium hydroxide, about 0.1% by weight to about 3% by weightof the alcohol compound, and about 15% by weight to about 20% by weightof the ethylenediamine-based chelating agent, and the UBM layer includestitanium (Ti).
 13. The method as claimed in claim 10, wherein thecomposition comprises about 75% by weight to about 83% by weight ofhydrogen peroxide, about 1% by weight to about 7% by weight of theaqueous basic solution including tetraalkylammonium hydroxide, about0.01% by weight to about 3% by weight of the alcohol compound, and about15% by weight to about 20% by weight of the ethylenediamine-basedchelating agent, and the UBM layer includes titanium tungsten (TiW). 14.The method as claimed in claim 10, wherein removing the portion of theUBM layer includes etching the UBM layer using the etching compositionat a temperature of about 40° C. to about 70° C. for about 1 minute toabout 5 minutes.
 15. The method as claimed in claim 10, after removingthe UBM layer, further comprising performing a heat treatment on thesubstrate on which the conductive bump is formed.
 16. The method asclaimed in claim 15, after performing the heat treatment, furthercomprising cleaning the bump structure using the etching composition ata temperature of about 20° C. to about 40° C. for about 30 seconds toabout 1 minute.
 17. The method as claimed in claim 10, wherein the UBMlayer comprises at least one of titanium tungsten (TiW), chromium (Cr),copper (Cu), titanium (Ti), nickel (Ni), nickel vanadium (NiV),palladium (Pd), chromium/copper (Cr/Cu), titanium tungsten/copper(TiW/Cu), titanium tungsten/gold (TiW/Ag) and nickel vanadium/copper(NiV/Cu).
 18. The method as claimed in claim 10, wherein the nonionicsurfactant includes a copolymer of polyethylene oxide and polypropyleneoxide or a block copolymer of polyethylene glycol and polypropyleneglycol.
 19. The method as claimed in claim 10, wherein the aqueous basicsolution includes about 25% by weight to about 50% by weight of ammoniumhydroxide or about 15% by weight to about 35% by weight oftetraalkylammonium hydroxide.
 20. The method as claimed in claim 10,wherein the pad includes aluminum and the passivation layer includes atleast one of polyimide or silicon oxynitride.